By tracking brain activity when an animal stops to look around its environment, neuroscientists at the Johns Hopkins University believe they can mark the birth of a memory. Using lab rats on a circular track, James Knierim, professor of neuroscience in the Zanvyl Krieger Mind/Brain Institute at Johns Hopkins, and a team of brain scientists noticed that the rats frequently paused to inspect their environment with head movements as they ran. The scientists found that this behavior activated¹ a place cell in their brain, which helps the animal construct a cognitive² map, a pattern of activity in the brain that reflects the animal's internal representation of its environment.

 

In a paper recently published by the journal Nature Neuroscience, the researchers state that when the rodents³ passed that same area of the track seconds later, place cells fired again, a neural⁴ acknowledgement that the moment has imprinted⁵ itself in the brain's cognitive map in the hippocampus（海马）.

 

The hippocampus is the brain's warehouse⁶ for long- and short-term processing of episodic（插话式的） memories, such as memories of a specific experience like a trip to Maine or a recent dinner. What no one knew was what happens in the hippocampus the moment an experience imprints⁷ itself as a memory.

 

"This is like seeing the brain form memory traces in real time," said Knierim, senior author of the research. "Seeing for the first time the brain creating a spatial⁸ firing field tied to a specific behavioral experience suggests that the map can be updated rapidly and robustly⁹ to lay down a memory of that experience."

 

A place cell is a type of neuron within the hippocampus that becomes active when an animal or human enters a particular place in its environment. The activation¹⁰ of the cells helps create a spatial（空间的） framework much like a map, that allows humans and animals to know where they are in any given location. Place cells can also act like neural flags that "mark" an experience on the map, like a pin that you drop on Google maps to mark the location of a restaurant.

 

"We believe that the spatial coordinates¹¹ of the map are delivered to the hippocampus by one brain pathway, and the information about the things that populate the map, like the restaurant, are delivered by a separate pathway," Knierim said. "When you experience a new item in the environment, the hippocampus combines these inputs¹² to create a new spatial marker of that experience."

点击收听单词发音